Sizing composition for use in papermaking



Patented May 7, 1946 SIZING COMPOSITION FOR USE IN PAPERMAKING Andrew J.Luettge'n, Saring Grove, Pm, assignor,

by mesne syl asllgnmen to P. H. Glaitelter Company, Spring Grove, Pa, acorporation of Penn- No Drawing. Application March 9, 1943, 1 Serial No.478,527

3 Claims. (Cl. 106-144) This invention relates to sizing compositionsfor use in Paper making. It provides a sizing material which isrelatively low in cost, may be made from readily available materials,is, particularly adapted for long storage or shipment prior to'use. andforms a paper of high-quality.

The sizing of paper is effected either by addin a sizing composition tothe paper pulp in. the beater before the pulp is formed into paper or bypassing formed paper through a bath of sizingmaterial. The latteroperation is generally known as "tub-sizing or calender-sizing." Thepresent invention is herein particularly described as applied to sizesintended for addition to the beater, but in certain circumstances it maybe. applicable to tub or calender-sizing as well.

Various materials for the sizin of paper have heretofore been proposed.Generally speaking, paper sizes intended for use in the beater are addedthereto in the Iormof emulsions and the sizing element is caused todeposit on the fiber by adding paper-makers alum to the. beater. Thecost of the size and the cost of the alum both bulk large in themanufacturing expense.

Sizes have been proposed involving the use of clay and wax, and othershave been proposed using rosin and clay; U. S. Patent to Walpuski, No.313,263, U. S. Patent to Manson, No. 1,990,457. It has also beenproposed to use a protective colloid, such as casein, in a sizecontaining, e. 'g., rosin and clay; U. S. Patent to Grasshof et al.. No.2,271,691. These andlike proposals havehad for manufacture in a Bewoi.found to be quite satisfactory for the purpose.

very stable, give rise to no paper defects when intelligently used andmay be made from clays less expensive and more readily available thanthose heretofore indicated. Moreover, my improved sizes are lessexpensive in themselves and may be precipitated in the beater with asmall amount of alum or other acidifler, thus eil'ecting a doublesaving.

I give below two specific examples of the mak- I ing of ,my improvedsize. l miile these may be made in any suitable mixer,fthe examples hereare mill, which I have Example 1.-'-Rosin size .(a) 50.1. 12 lbs. oflactic casein in 9 gals. of water at '15-80'F. forabout 5 minutes. Add9% oz. of caustic soda dissolved in a gallonvof-water to the casein andheat the mixture to about 100 F. with direct steam. This gives a totalvolume of casein solution of about 10 gals.

(D) From a rosin melting tank draw the equivv alent of 430 lbs. of rosininto the mixer. Start several shortcomings. Sizes-made according to thedisclosures mentioned are unstable, a large part of the solids tendingto separate'out after a limited period of time, with the result that thesizes become either wholly unsatisfactory for use or else result in theproduction of an inferior grade of paper or are unsuited for longstorage or for shipment over any considerable distance; or in their usecause rosin specks" in the paper; or require the use of speciallyprepared clays of a. colloidal nature; see, for example, the Manson andGrasshof et al. patents above mentioned. The Manson patent involves theuse of colloidal clay. Such clays have a maximum particle size of thegeneral order of micron. The Grasshoi et al. patent employselectro-osmotically treated clay so as to attain a particle size of adiameter much less than 1 micron. Clays of the kinds.

the high-speed agitator at 280 to 300 R. P. M. and

maintain a temperature of approximately 250 F. in the mixer.

(c) Add 6 lbs. of caustic dissolved in 1 to 1% gals.of.water, takingcare to add the caustic slowly enough to avoid excess foaming andsplashing.

As the causticsolution is being added to the mixer, heat thecaseinsolution to approximately 150 F. and at the same time heat waterin an auxiliary vessel gals. capacity is suillcient) to approximately130 F.

((1) Add to the mixer 215 lbs. of either "Satin" or Cosmic A" grade clay(hereinafter. de-- scribed) by running the mill at high speed and addingthe clay as fast as good mixing permits.

The temperature of the mix "at this point should not be above 220 F. Ifany difllculty is encountered in lowering the temperature to thisfigure. a. thin stream of cold water may be directed into the mill whilethe clay is being addedtherebelow. It will be found that the mixthickens and the agitation becomes diilicult. Then stir the caseinsolution into the mix. It-will be found that the level-of the mix willdrop several inches on this addition. Now add water from the auxiliaryvessel until the mix is away from the shaft and has asmooth appearance.The water should be added cautiously because better results If the sizeis to be stored for any considerable length of time, a suitablepreservative, e. g.

formaldehyde (1 quart), should be added in the.

last stage of mixing.

The concentrated size may be added directly to the beater, or it may beextended with cold water before use. I have found it convenient toextend the size so that it can be metered through a gasoline measuringpump. .This can be done with size previously made up, or it may be doneas a final step of the manufacture. In this latter case, following step(1) above, I shift. the Bewoid mill to slow speed and then start addingwater at a slow rate and at a temperature of about 85 F. The use of theslow speed avoids spilling over'as this water is added. After about 8gals. I

of water have been added, the rate at which it is added may bematerially increased. The addition of water is continued until thedesired percentage of solids has been added. I find that a sizecontaining about 50% solids may be readily handled in a gasolinemeasuring pump.

Example 2.Wa:r size (a) Heat 210 lbs. of ordinary scale wax" .(unrefinedparaflln of low melting point) to 200 1". in the mill and start theagitator at high speed. Add 105 lbs. of clay, such as Satin" or CosmicA," and mix it thoroughly. The temperature at this point should bebetween 190 and 200 F.

(D) Add 25 lbs. of Ammonia Soap C (from Harshaw Chemical Company ofCleveland, Ohio) and continue the mixing.

In the meantime, allow 25 lbs. of lactic casein to swell in water andcut with 1% lbs. of caustic soda at 120 to 140 F. Before adding the cutcasein to the mix, heat the casein solution to 160-170 F. Add it rapidlyto the mix, using high-speed agitation. The temperature atthis pointshould be about 175 F.

(d) Add water at a temperature of 170 to 175 F. with high-speed mixing.The precise amolmt is gauged by appearance, water being added until themix smooths out. This will ordinarily require from 2% to 6 gals. As soonas the-mix has smoothed out, stop adding water. Continue the high-speedagitation for about minutes.

Ii the size is to be stored for a considerable manufacture of the sizeto form an admixture of the fusible binding agent and the clay with acompatible soap prior to the addition of the protective colloid. Themixing of the binding agent, the clay and the soap is effected at atemperature above the fusing point of the binding agent. Preferably, theprotective colloid is added when the mix is at a temperature below thatat which the major portion of the mixing is done. The procedure Justoutlined improves the quality of the size and, where saponiflcation ofrosin is effected in the mill, minimizes the possibility of impairmentof the protective colloid, e. g., by hydrolysis.

Factors of my invention requiring detailed discussion are particle sizeand quantity of clay employed, concentration of the size and ratiobetween the amount of protective colloid used and the amount of alkaliemployed to cut it. By giving due regard to these factors, a size whichremains stable over a long period of time and will yet go into solutionreadily, which is low in cost and which gives a high quality of papermay be 7 obtained.

Particle size and quantity of clay employed.- The fact that the claysemployed need not have particles of such minute dimensions as heretoforefound necessary is a commercial important aspect of my invention. I havesuccessfully used Georgia clays from the McIntyre district, produced byEdgar Brothers Company of Metuchen, New Jersey, and known commerciallyas their Satin" and Cosmic A" grades. Satin" has particles as large asabout 4 microns, some 5% of the clay by weight ranging down to 2microns. Cosmic A is finer, but has particles as large as about 2.5 or 3microns, some 8-10% of the clay by weight ranging down to 1 micron.These and similar clays are readily available in quantity in the UnitedStates, whereas, so far as I am aware. electro-osmotically separatedclays are not available in this country, except possibly on alaboratoryscale, and, if obtainable at all, are prohibitive in'price.

My invention not only permits of using lessexpensive clays, but also ofusing a relatively period before using, add a preservative, e. g. a

lquart of formaldehyde, in the last stage of mix- In lieu of rosin orparailln wax, other fusible binding agents such as other natural andsynthetic resins and waxes other than parailln may be used. This is afeature of importance because it permits of using materials most readilyavailable at any particular time. Bituminous or petroleum distillatematerials are generally unsuitable. Among other limitations. they areusually so strongly colored that they make the final paper colorunsuitable for most purposes. 4

The initial addition of caustic in the rosin size (step b of Example 1above) results in a saponiflcation of a part of the rosin. Instead ofproceeding in this fashion, it is permissible to retofore. The clayswhich I amable to employ cost considerably less per ton. than thefusible binding agents employed and it is therefore commerciallyadvantageous to use a high percentage of clay in the size. My inventionmakes it possible to use clay in the amount of 50% of the weight of thebinding agent, or even more provided that a sufficiently rugged mixer isavail able.

A size made according to my invention and Indeed, it should not bepermitted even to have,

in the fluid state, an unduly high concentration.

The maximum permissible concentration is about 70% solids and for mostpurposes I prefer a concentration of about 65% solids. In concentrationsgreater than 70% the size proves exceedingly difficult to handle,particularly in cold weather, and if brought to the solid state it isvery resistant to going into uniform suspension in water of anytemperature sufflciently low, to inhibit coalescence of the, rosin.

I do nothazard any theory which would account for this differencebetween my size and those heretofore proposed. It may be due to the factthat I use coarser clays or to the difference in the order ofmanufacturing steps. At any rate, it indicates a marked difference inthe character of the products.

At concentrations of 60-70% my size is remarkably stable and despite thefact that it contains clay particles ranging up to 2.5-3 or even 4microns, it may be shipped, handled and stored over a period of monthswithout losing the character of a substantially uniformviscous fluidfree from aggiomerations or sediment.

My size is readily receptive to the addition of a freezing-pointdepressant, such as ethylene glycol, which may be adde lii it is desiredto protect the size against freezing in cold weather. If no depressantis added, the size will tend to sepggate if exposed to temperaturesmaterially below Even if extended to a lesser concentration than60-7ti%, the size remains stable for a considerable period of time. Inthe more dilute forms of the size there issome advantage in the use ofCosmic A clay over Satin clay. At a concentration of for extending thesize in quantities for storage and U58.

none of protective colloid to alkali-The Sta bility of the size and itshigh quality in general will be diminished unless due precautions aretaken in its manufacture to observe limiting ratios between the amountof protective colloid used and the amount of caustic employed to cut it.

The protective colloid which I prefer to use is casein, but I may useother proteins, e. g. albumen, vegetable proteins such as those derivedfrom the soy bean, and gelatin. These proteins are effective protectivecolloids overa wide range of conditions, but in order to achieve mydesired resuits the cutting of the colloid must be ,care- .iullycontrolled so that it neither forms aggregates of denatured protein orhydrolyzes. specific example, as between lactic casein and caustic soda(on an anhydrous basis), the ratio by weight should be a minimum ofabout 20 casein to 1 of caustic; and a maximum of about 40 casein to' 1of caustic; that is to say. the caustic should not exceed about 5% ofthe weight of the By way of casein. or be less than about 2/z%; Betterresults will be obtained with the higher figure. It will be found thatthe ratio will differ with different protein protective colloids, andvary somewhat depending on the amount of acid impurities in the colloid(casein). but in each case the principles to be observed are (a) thatformation of aggregates of denatured protein,- on the one hand,

tion in viscosity which I believe-to be due to hydrolysis of asubstantial part of the casein.

In placeof caustic soda other alkalis, for example caustic potash, oralkaline salts, for example soda ash, may be used to cut the casein, andI comprehend these by the term "alkaline cutting agent. In any case, therule just stated remains applicable.

My invention makes it possible, by controlling the factors ofparticle'size a'nd of concentration,

and by observing the principles herein stated as to the cutting of theprotective colloid, to make a paper sizing composition which does notdeteriorate and is remarkably stable. It is therefore in discharging itfrom the tank cars in which it is shipped, whereas sizes now on themarket, such as rosin soap sizes, must be shipped in special cars andheated therein before it is possible to unload it. My improved size isreadily mixable with water at room temperature and'no' dimculty isencountered in extending it either in the heater or preliminarily. It isthus admirably suited for quick use in the paper mill. My size isrelatively low in cost. It is made from materials whichare all availablein adequate quantities and in such form that the raw material cost islow. As to the several ingredients used, the higher priced ones are inminimum quantity. The manufac-' turing cost is low and the shipping andstorage costs are likewise low. The emciency of the size, pound forpound, is higher than that of sizes heretofore employed so that a lesserquantity may be used. The alum. reuuirementsare correspondinglylessened, but the principal saving in alum is dueto the fact that thealum requirements per pound are markedly-low. The use of my improvedsize results in the production ofpaper of high quality, well sized andtree from rosin specks.

I have described two present preferred embodiments or my invention. Itwill be understood, howeven'that these are by way of example only andthat the invention may be .otherwise embodiedwithin the scope of thefollowing claims.

I claim:

l. A sizing composition for use in paper making, in theform of anaqueous suspension and comprising a binding agent selected from'theclass consisting of the fusible resins and waxes, clay in the form oifine particles, there being particles as large as 2.5 microns, acompatible soap and a proteinaceousprotective colloid, the colloid being cut with an alkaline cutting agent in the amount of 2V: to 5 percent of the weight or the colloid so that hydrolysis of the colloid and10mmtion of negates of denatured protein are inhibited, whereby the sizeof the individual par ticles in the sizing composition is uniformlysmall.

2. A sizing composition for use in paper making, in the form of anaqueous suspension and comprising a binding agent selected from theclass consisting of the fusible resins and waxes,-clay in the form offine particles, there being particles as large as 2.5 microns, acompatible soap and casein cut with an alkaline cutting agent in theamount of 2 /2 to 5 per cent of the weight of the casein, Y

clay in the form of fine particles, there being particles as large as2.5 microns, a compatible soap and lactic casein out. with caustic sodain the amount of 2 /2 to 5 per cent of the weight of the casein, wherebythe size of the individual particles in the sizing composition isuniformly small.

ANDREW J. LUETTGEN.

